<div>Fractal theory provides a new strategy for the equipment design and
industrial amplification. In this work we propose a novel H-like fractal
(HLF) impeller to improve the distribution uniformity of hydrodynamics
in stirred tanks. The impeller with two vertical blades becomes fractal
impellers by designing each vertical blade as an H-shaped sub-blade
(HLF-1) or uniform arrangement of H-shaped sub-blades (HLF-2). Flow
characteristics including velocity and turbulent kinetic energy (TKE)
distributions, vortices, power number, are predicted by large eddy
simulation. Compared with Rushton turbine (RT) impeller when
<i>H</i>/<i>T</i>=1 (or dual RTs when <i>H</i>/<i>T</i>=1.5, triple RTs
when <i>H</i>/<i>T</i>=2), the HLF impeller can produce a flow field
with more uniform distributions of larger velocities and TKE level. The
HLF-2 impeller can further improve distribution uniformity of
hydrodynamics in the case of high <i>H</i>/<i>T</i>. Power analysis
shows that this is mainly due to the improved energy utilization
efficiency by the fractal structure design.</div>